The black rat came to Northern Europe first--both of them probably being Asiatic animals--and has no doubt been to some extent replaced by the brown rat, who has been specially favoured by the modern extension of drains and sewers, which exactly suit his peculiar tastes. But each flourishes in his own environment; neither of them is adapted to the other's environment; there is no war between them, nor any occasion for war, for they do not really come into competition with each other. The cockroaches, or "blackbeetles," furnish another example. These pests are comparatively modern and their great migrations in recent times are largely due to the activity of human commerce. There are three main species of cockroach--the Oriental, the American, and the German (or Croton bug)--and they flourish near together in many countries, though not with equal success, for while in England the Oriental is most prosperous, in America the German cockroach is most abundant. They are seldom found in actual association, each is best adapted to a particular environment; there is no reason to suppose that they fight. It is so throughout Nature. Animals may utilise other species as food; but that is true of even, the most peaceable and civilised human races. The struggle for existence means that one species is more favoured by circumstances than another species; there is not the remotest resemblance anywhere to human warfare. We may pass on to the second claim for war: that it is an essential factor in the social development of primitive human races. War has no part, though competition has a very large part, in what we call "Nature." But, when we come to primitive man the conditions are somewhat changed; men, unlike the lower animals, are able to form large communities--"tribes," as we call them--with common interests, and two primitive tribes can come into a competition which is acute to the point of warfare because being of the same, and not of two different, species, the conditions of life which they both demand are identical; they are impelled to fight for the possession of these conditions as animals of different species are not impelled to fight. We are often told that animals are more "moral" than human beings, and it is largely to the fact that, except under the immediate stress of hunger, they are better able to live in peace with each other, that the greater morality of animals is due. Yet, we have to recognise, this mischievous tendency to warfare, so often (though by no means always, and in the earliest stages probably never) found in primitive man, was bound up with his superior and progressive qualities. His intelligence, his quickness of sense, his muscular skill, his courage and endurance, his aptitude for discipline and for organisation--all of them qualities on which civilisation is based--were fostered by warfare. With warfare in primitive life was closely associated the still more fundamental art, older than humanity, of dancing.